hi hannu
i find i can sometimes play a whole round in my head now if laying in my bed if sitting i get distracted to easy. what i did at first was to concentrate on the holes i use to find hard, you often can work out how to play them by thinking them through and i also think of having bad shots too and playing the next shot from rough or bunkers.
i found it hard to concentrate more when on the golf course when i had to see the shot before i played it, that took more time to develop but will come with time if you keep doing it, you sometimes get the feeling you have played the hole before you have hit the ball and its surprising how often you see the shot before hand and you feel relaxed and hit the shot as planed.
i think the big benefit is in relaxing your body and mind and it lets your mind take over the shot and you mind reacts so much faster then if you try and command it to do something.
i have been using this system over 20 years and it was Jack Nicklaus that that i copied it from.
cheers
bill

__________________
ping zing2 metal driver
ping zing2 metal 3 wood
ping eye2 1 iron
ping zing2 3/9 irons
ping ist 47% wedge
ping zing2 52% s/wedge
ping mb 56% wedge
ping c10 G2I broom handled putter
top flight "T" golf balls
white ping bag